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Optimization of the SNR-resolution tradeoff for registration of magnetic resonance images

HUMAN BRAIN MAPPING 2008年第10期29卷 1147-1158页

作者： Kale, Shoan C. Lerch, Jason P. Henkelman, R. Mark Chen, X. Josette Hosp Sick Children Mouse Imaging Ctr Toronto ON M5G 1X8 Canada Univ Toronto Dept Med Biophys Toronto ON Canada

image registration serves many applications in medical imaging, including longitudinal studies, treatment verification, and more recently, morphometry. Registration processing is regularly applied in magnetic resonance (MR) images, where imaging is highly adaptable in capturing soft tissue contrast. To obtain the greatest registration accuracy in MR imaging, the inherent imaging tradeoff between SNR and resolution at a given scan time should be optimized for computational accuracy, rather than human viewing. We investigated this SNR-resolution tradeoff to optimize registration for digital morphometry. Tradeoff images were simulated from acquired gold standard MR images to emulate a shorter, constant acquisition time, but at the expense of SNR, resolution, or both. The group of images from each tradeoff was nonlinearly registered toward an average atlas producing deformation fields, useful for identifying differences in morphology. The gold standard data were also registered. The deformation fields were used to evaluate registration performance of each tradeoff relative to the gold standard. For fixed scan times, the optimal SNR for registration with MR imaging was found to be similar to 20. image resolution should be adjusted to produce this target voxel SNR when registration is a central processing task.

关键词： brain mapping atlases computer-assisted image processing computer simulation phenotype

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NEMA NU 1-2018 performance characterization and Monte Carlo model validation of the Cubresa Spark SiPM-based preclinical SPECT scanner

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EJNMMI PHYSICS 2023年第1期10卷 35页

作者： Strugari, Matthew E. E. DeBay, Drew R. R. Beyea, Steven D. D. Brewer, Kimberly D. D. Biomed Translat Imaging Ctr Halifax NS Canada Dalhousie Univ Dept Phys & Atmospher Sci Halifax NS Canada Cubresa Inc Winnipeg MB Canada Dalhousie Univ Dept Diagnost Radiol Halifax NS Canada Dalhousie Univ Sch Biomed Engn Halifax NS Canada Dalhousie Univ Dept Microbiol & Immunol Halifax NS Canada

Background: The Cubresa Spark is a novel benchtop silicon-photomultiplier (SiPM)-based preclinical SPECT system. SiPMs in SPECT significantly improve resolution and reduce detector size compared to preclinical cameras with photomultiplier tubes requiring highly magnifying collimators. The NEMA NU 1 Standard for Performance Measurements of Gamma Cameras provides methods that can be readily applied or extended to characterize preclinical cameras with minor modifications. The primary objective of this study is to characterize the Spark according to the NEMA NU 1-2018 standard to gain insight into its nuclear medicine imaging capabilities. The secondary objective is to validate a GATE Monte Carlo simulation model of the Spark for use in preclinical SPECT studies. Methods: NEMA NU 1-2018 guidelines were applied to characterize the Spark's intrinsic, system, and tomographic performance with single- and multi-pinhole collimators. Phantoms were fabricated according to NEMA specifications with deviations involving high-resolution modifications. GATE was utilized to model the detector head with the single-pinhole collimator, and NEMA measurements were employed to tune and validate the model. Single-pinhole and multi-pinhole SPECT data were reconstructed with the Software for Tomographic image Reconstruction and HiSPECT, respectively. Results: The limiting intrinsic resolution was measured as 0.85 mm owing to a high-resolution SiPM array combined with a 3 mm-thick scintillation crystal. The average limiting tomographic resolution was 1.37 mm and 1.19 mm for the single- and multi-pinhole collimators, respectively, which have magnification factors near unity at the center of rotation. The maximum observed count rate was 15,400 cps, and planar sensitivities of 34 cps/MBq and 150 cps/MBq were measured at the center of rotation for the single- and multi-pinhole collimators, respectively. All simulated tests agreed well with measurement, where the most considerable deviations were b

关键词： Molecular imaging Nuclear medicine SPECT Animal imaging instrumentation Monte Carlo method computer-assisted image processing Imaging phantoms

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Age estimation by volumetric analysis of teeth using cone beam computed tomography

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ORAL RADIOLOGY 2024年第3期40卷 436-444页

作者： Souza, Ana Beatriz Raposo Cruz, Adriana Dibo Aguiar, Marcelo Freitas Fluminense Fed Univ Hlth Inst Nova Friburgo Grad Program Dent Nova Friburgo RJ Brazil Fluminense Fed Univ Hlth Inst Nova Friburgo Grad Program Dent 22 Ctr BR-28625650 Nova Friburgo RJ Brazil Fluminense Fed Univ Hlth Inst Nova Friburgo Dept Specif Format Nova Friburgo RJ Brazil

Objectives To evaluate the feasibility of using the pulp volume (Pv) to total volume (Tv) ratio (Pv:Tv), obtained from cone beam computed tomography (CBCT) scans of single-rooted teeth, for age estimation in a Brazilian population sample. Methods After obtaining approval from the ethics committee, the study commenced by applying inclusion criteria to screen CBCT scans, resulting in a probability-based sample of participants aged 18 years and older (ranging from 18 to 82 years, with a mean age of 46.44 years). A total of 517 single-rooted teeth, including maxillary central incisors (CI), mandibular canines (C), and mandibular first premolars (FP), were chosen based on excellent agreement values (> 0.9). Pv and Tv measurements were conducted using semi-automatic segmentation with ITK-SNAP 3.8 software. Statistical analysis was performed using Jamovi software, with a significance level set at 5% (alpha = 0.05). Results A strong negative correlation (r > -0.7) was observed between chronological age and the Pv:Tv ratio across all examined teeth. However, when conducting regression analysis with Pv:Tv data and chronological age as the independent variable, only the mandibular FP teeth exhibited a normal distribution. The resulting linear model demonstrated moderate predictive value (approximately 64%) in explaining the variance in chronological age, but caution should be exercised when interpreting these findings. Conclusions The method of measuring individual tooth volume using CBCT to estimate chronological age via Pv:Tv has been demonstrated as effective and reproducible within the Brazilian population sample.

关键词： Aging Cone-beam computed tomography Diagnostic imaging computer-assisted image processing Forensic dentistry Tooth

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Segmentation of lung lobes in clinical CT images

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INTERNATIONAL JOURNAL OF computer assisted RADIOLOGY AND SURGERY 2008年第1-2期3卷 151-163页

作者： Wei, Qiao Hu, Yaoping MacGregor, John H. Gelfand, Gary Univ Calgary Schulich Sch Engn Calgary AB T2N 1N4 Canada Univ Calgary Fac Med Dept Radiol Calgary AB T2N 4N1 Canada Univ Calgary Foothills Med Ctr Cardiovasc Serv Dept SurgFac Med Calgary AB T2N 4N1 Canada Univ Calgary Foothills Med Ctr Thorac Surg Serv Dept SurgFac Med Calgary AB T2N 4N1 Canada

Objective Recent studies have shown that three-dimensional (3D) visualization of lung cavities has distinct advantages over multiplanar computed tomographic (CT) images for surgical planning. A crucial step for achieving this 3D visualization is the automatic segmentation of lung lobes. This paper presents a watershed algorithm for segmenting lung lobes in clinical CT images so that the 3D visualization of lung lobes would be practical in clinical settings. Materials and methods The watershed algorithm uses a two-stage approach to automatically identify the lobar fissures (boundaries of the lung lobes): (a) adaptive fissure sweep to coarsely define fissure regions of the lobar fissures;and (b) watershed transform to refine the location and curvature of the fissures within the fissure regions. Results The algorithm's feasibility was tested using six CT datasets. Compared to visual inspection, the watershed algorithm achieved an accuracy of 85.5-95.0, 88.2-92.3 and 100% for segmenting the left oblique, the right oblique, and the right horizontal fissures, respectively. The total computational time for both lungs was under 3 min. Conclusion We developed an autonomous algorithm for segmenting lung lobes. This algorithm provided promising potential for developing an automatic algorithm for segmenting lung lobes in clinical settings.

关键词： Lung cancer computer-assisted image processing CT X-ray

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computer-assisted VIDEO ANALYSIS OF [H-3]SPIROPERIDOL BINDING AUTORADIOGRAPHS

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JOURNAL OF NEUROSCIENCE METHODS 1984年第3期10卷 173-188页

作者： ALTAR, CA WALTER, RJ NEVE, KA MARSHALL, JF UNIV CALIF IRVINE DEPT PSYCHOBIOL IRVINE CA 92717 USA UNIV CALIF IRVINE DEPT DEV & CELL BIOL IRVINE CA 92717 USA

A computer-based video image processing system is described that quantifies the binding of the neuroleptic drug, [3H]spiroperidol, to rat forebrain sections. Adjacent sections were incubated in buffer containing [3H]spiroperidol or [3H]spiroperidol plus 1 .mu.M (+)-butaclamol and exposed to [3H]-sensitive film to produce autoradiographs of total binding or non-butaclamol-displaced (non-specific) binding. The image processing system digitized each autoradiograph, attenuated geometric distortion and unevenness of background illumination and reassigned the digitized image intensities (gray values) to be a linear function of fmol [3H]spiroperidol bound per mg protein by using a calibration curve generated from 3H-containing tissue standards. An image of butaclamol-displaced (specific) [3H]spiroperidol binding was produced by subtracting the linearized image of non-specific binding from the superimposed image of total binding. An image of percent specific [3H]spiroperidol binding was obtained by dividing the image of specific binding by the superimposed image of total binding. The computer-derived images, which could be displayed in gray tones or pseudocolor-coded, revealed that the greatest amounts of specific [3H]spiroperidol binding (1000-300 fmol/mg protein;60-80% specifically bound) were located in layers 5A and 5C of the neocortex, the claustrum and in the caudate-putamen, where a lateral-to-medial binding gradient occurred. [3H]Spiroperiodol was bound to a lesser extent (400-1000 fmol/mg protein;31-51% specifically bound) to the medial nucleus accumbens septi or olfactory tubercle and without measurable specificity to the lateral septum, anterior commissure, corpus callosum or superficial neocortex. These procedures are particularly useful for the quantitative and visual analysis of autoradiographs in which [3H]ligand binding is associated with more than a single site.

关键词： computer-assisted image processing receptor binding neostriatum autoradiography spiroperidol basal ganglia

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Quantification of airway wall contrast enhancement on virtual monoenergetic images from spectral computed tomography

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EUROPEAN RADIOLOGY 2023年第8期33卷 5557-5567页

作者： Bodenberger, Arndt Lukas Konietzke, Philip Weinheimer, Oliver Wagner, Willi Linus Stiller, Wolfram Weber, Tim Frederik Heussel, Claus Peter Kauczor, Hans-Ulrich Wielpuetz, Mark Oliver Heidelberg Univ Hosp Dept Diagnost & Intervent Radiol Neuenheimer Feld 420 D-69120 Heidelberg Germany Translat Lung Res Ctr Heidelberg TLRC German Ctr Lung Res DZL Neuenheimer Feld 156 D-69120 Heidelberg Germany Thoraxklin Univ Heidelberg Dept Diagnost & Intervent Radiol Nucl Med Rontgenstrasse 1 D-69126 Heidelberg Germany

ObjectivesQuantitative computed tomography (CT) plays an increasingly important role in phenotyping airway diseases. Lung parenchyma and airway inflammation could be quantified by contrast enhancement at CT, but its investigation by multiphasic examinations is limited. We aimed to quantify lung parenchyma and airway wall attenuation in a single contrast-enhanced spectral detector CT *** this cross-sectional retrospective study, 234 lung-healthy patients who underwent spectral CT in four different contrast phases (non-enhanced, pulmonary arterial, systemic arterial, and venous phase) were recruited. Virtual monoenergetic images were reconstructed from 40-160 keV, on which attenuations of segmented lung parenchyma and airway walls combined for 5th-10th subsegmental generations were assessed in Hounsfield Units (HU) by an in-house software. The spectral attenuation curve slope between 40 and 100 keV (lambda HU) was *** lung density was higher at 40 keV compared to that at 100 keV in all groups (p < 0.001). lambda HU of lung attenuation was significantly higher in the systemic (1.7 HU/keV) and pulmonary arterial phase (1.3 HU/keV) compared to that in the venous phase (0.5 HU/keV) and non-enhanced (0.2 HU/keV) spectral CT (p < 0.001). Wall thickness and wall attenuation were higher at 40 keV compared to those at 100 keV for the pulmonary and systemic arterial phase (p <= 0.001). lambda HU for wall attenuation was significantly higher in the pulmonary arterial (1.8 HU/keV) and systemic arterial (2.0 HU/keV) compared to that in the venous (0.7 HU/keV) and non-enhanced (0.3 HU/keV) phase (p <= 0.002).ConclusionsSpectral CT may quantify lung parenchyma and airway wall enhancement with a single contrast phase acquisition, and may separate arterial and venous enhancement. Further studies are warranted to analyze spectral CT for inflammatory airway diseases.

关键词： Multidetector computed tomography Lung Contrast material computer-assisted image processing

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Optimization of techniques for the maximal detection and quantification of Alzheimer's-related neuropathology with digital imaging

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NEUROBIOLOGY OF AGING 2002年第2期23卷 161-170页

作者： Cummings, BJ Mason, AJL Kim, RC Sheu, PCY Anderson, AJ Univ Calif Irvine Dept Pathol Irvine CA 92697 USA Univ Calif Irvine Inst Brain Aging Irvine CA 92697 USA

Prior to undertaking quantitative neuropathological studies of Alzheimer's disease, methods for detecting plaques and tangles must be optimized. While suitable antibodies have been developed with great sensitivity, specificity, and reliability, there is no standard pretreatment protocol for key AD-related pathology, It is well known that formic acid treatment enhances the detection of beta-amyloid. But what concentration of formic acid is best;can similar methods enhance the detection of tau-related pathology? This study compared multiple antigen retrieval techniques (e.g. boiling in citrate or glycine buffer, microwaves, formic acid concentrations), to develop an optimal, standardized protocol for quantitative digital microscopy. Free-floating (40 mum) and paraffin-embedded (12 mum) sections of formalin fixed frontal cortex from mild, moderate, and severe AD cases (n = 18) were pretreated with fifteen different protocols and stained with each of the following antibodies: beta42, PHF-1, MC-1 and AT8. Random fields were digitally captured and images were thresholded to select for positively stained areas versus background (e.g. "load"). As previously reported, high concentrations of formic acid were extremely effective in enhancing the detection of P-amyloid as much as a 2-fold enhancement in Abeta "load" values were observed. Surprisingly, tau-related pathology detection also increased significantly following pretreatment. Depending on the antibody, between a 3-fold and 6-fold enhancement was possible relative to no pretreatment. Comparable results were found in paraffin-embedded sections. Similar enhancements in the detection of pathology were obtained following 99% formic acid exposure, microwaving in citrate buffer (pH 9.0) or exposure to 99% formic acid then boiling in citrate buffer (pH 6.0). Because the latter treatments were often harsh on the tissue and more difficult to control, we recommend a standard tissue pretreatment of 99% formic acid for seven minute

关键词： Alzheimer's disease neuropathology quantification senile plaques neurofibrillary tangles immunocytochemistry technique computer-assisted image processing comparative study reference values

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Automated brain volumetric program measuring regional brain atrophy in diagnosis of mild cognitive impairment and Alzheimer's disease dementia

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BRAIN IMAGING AND BEHAVIOR 2022年第5期16卷 2086-2096页

作者： Ryu, Dong-Woo Hong, Yun Jeong Cho, Jung Hee Kwak, Kichang Lee, Jong-Min Shim, Yong S. Youn, Young Chul Yang, Dong Won Catholic Univ Korea Coll Med Dept Neurol 222 Banpo Daero Seoul 06591 South Korea Hanyang Univ Dept Biomed Engn Seoul South Korea Chung Ang Univ Hosp Dept Neurol Seoul South Korea

A quantitative analysis of brain volume can assist in the diagnosis of Alzheimer's disease (AD) which is ususally accompanied by brain atrophy. With an automated analysis program Quick Brain Volumetry (QBraVo) developed for volumetric measurements, we measured regional volumes and ratios to evaluate their performance in discriminating AD dementia (ADD) and mild cognitive impairment (MCI) patients from normal controls (NC). Validation of QBraVo was based on intra-rater and inter-rater reliability with a manual measurement. The regional volumes and ratios to total intracranial volume (TIV) and to total brain volume (TBV) or total cerebrospinal fluid volume (TCV) were compared among subjects. The regional volume to total cerebellar volume ratio named Standardized Atrophy Volume Ratio (SAVR) was calculated to compare brain atrophy. Diagnostic performances to distinguish among NC, MCI, and ADD were compared between MMSE, SAVR, and the predictive model. In total, 56 NCs, 44 MCI, and 45 ADD patients were enrolled. The average run time of QBraVo was 5 min 36 seconds. Intra-rater reliability was 0.999. Inter-rater reliability was high for TBV, TCV, and TIV (R = 0.97, 0.89 and 0.93, respectively). The medial temporal SAVR showed the highest performance for discriminating ADD from NC (AUC = 0.808, diagnostic accuracy = 80.2%). The predictive model using both MMSE and medial temporal SAVR improved the diagnostic performance for MCI in NC (AUC = 0.844, diagnostic accuracy = 79%). Our results demonstrated QBraVo is a fast and accurate method to measure brain volume. The regional volume calculated as SAVR could help to diagnose ADD and MCI and increase diagnostic accuracy for MCI.

关键词： Alzheimer's disease Dementia Cognitive dysfunction Magnetic resonance imaging computer-assisted image processing

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Parameter optimization of a computer-aided diagnosis system for detection of masses on digitized mammograms

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TECHNOLOGY AND HEALTH CARE 2015年第6期23卷 757-774页

作者： Radovic, Milos Milosevic, Marina Ninkovic, Srdjan Filipovic, Nenad Peulic, Aleksandar Univ Kragujevac Kragujevac Serbia Res & Dev Ctr Bioengn Kragujevac Serbia Clin Ctr Kragujevac Kragujevac Serbia

BACKGROUND: Reading mammograms is a difficult task and for this reason any development that may improve the performance in breast cancer screening is of great importance. OBJECTIVE: We proposed optimized computer aided diagnosis (CAD) system, equipped with reliability estimate module, for mass detection on digitized mammograms. METHODS: Proposed CAD system consists of four major steps: preprocessing, segmentation, feature extraction and classification. We propose a simple regression function as a threshold function for extraction of potential masses. By running optimization procedure we estimate parameters of the preprocessing and segmentation steps thus ensuring maximum mass detection sensitivity. In addition to the classification, where we tested seven different classifiers, the CAD system is equipped with reliability estimate module. RESULTS: By performing segmentation 91.3% of masses were correctly segmented with 4.14 false positives per image (FPpi). This result is improved in the classification phase where, among the seven tested classifiers, multilayer perceptron neural network achieved the best result including 77.4% sensitivity and 0.49 FPpi. CONCLUSION: By using the proposed regression function and parameter optimization we were able to improve segmentation results comparing to the literature. In addition, we showed that CAD system has high potential for being equipped with reliability estimate module.

关键词： Breast cancer computer-assisted image processing data mining mammography optimization

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MR-based tridirectional flow imaging. Acquisition and 3D analysis of flows in the thoracic aorta

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RADIOLOGE 2007年第11期47卷 1012-1020页

作者： Unterhinninghofen, R. Ley, S. Frydrychowicz, A. Markl, M. Univ Karlsruhe Inst Informat Technol D-76131 Karlsruhe Germany Deutsch Krebsforschungszentrum Abt Radiol E010 Heidelberg Germany Univ Kinderklinik Heidelberg Pediat Radiol Heidelberg Germany Univ Freiburg Klinikum Rontgendiagnost Abt Freiburg Germany

Tridirectional MR flow imaging is a novel method that extends the well-established technique of phase-contrast flow measurement by vectorial velocity encoding, i.e., by encoding in all three spatial directions. Modern sequence protocols allow the acquisition of velocity vector fields with high spatial resolutions of 1-3 mm and temporal resolutions of 20-50 ms over the heart cycle. Using navigating techniques, data on the entire thoracic aorta can be acquired within about 20 min in free breathing. The subsequent computer- based data processing includes automatic correction of aliasing effects, eddy currents, gradient field inhomogeneities, and Maxwell terms. The data can be visualized in three dimensions using vector arrows, streamlines, or particle traces. The parallel visualization of morphological slices and of the surface of the vascular lumen in 3D enhances spatial and anatomical orientation. Furthermore, quantitative values such as blood flow velocity and volume, vorticity, and vessel wall shear stress can be determined. Modern software systems support the integrated flow-based analysis of typical aortic pathologies such as aneurysms and aortic insufficiency. To what extent this additional information will help us in making better therapeutic decisions needs to be studied in clinical trials.

关键词： computer-assisted image processing blood circulation blood flow velocity pulsatile flow

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